Question: 9 notebooks cost $9.27. Which equation would help determine the cost of 2 notebooks?
There are several equations that could help determine the cost, each with a slightly different approach. We can write the fact that 9 notebooks cost $9.27 as a proportion: $\dfrac{9}{\$9.27}$ Let $x$ represent the unknown cost of 2 notebooks. Since 2 notebooks cost $x$ , we have the following proportion: $\dfrac{2}{x}$ The cost changes along with the number of notebooks purchased, and so the two proportions are equivalent. $\dfrac{9}{\$9.27} = \dfrac{2}{x}$